Maintaining weight loss after the initial phases of any weight loss intervention is a challenge. Rationally, it depends on how well the adherence is to the prescribed treatment. This study is to test the sustainability of an intervention in maintaining weight lost during Ramadan by using voluntary fasting. Methods: Two groups of respondents (Muslim women with body mass index (BMI) ≥ 25.0 kg/m2) were randomly recruited from two states in Malaysia. One group received the Islamic based intervention (Group A) and the other received the standard intervention (Group B). The intervention consisted of three phases. The first phase was the intensive phase which was the control of food quantity intake during the fasting month of Ramadan. The second phase was the maintenance phase where the respondents were assisted to continue monitoring their food consumption using the food diary for 3 months and the third phase was the following 3 months without any assistance. The variables studied were BMI, blood pressure (systolic and diastolic pressure) and selected blood biochemical (i.e. total cholesterol (TC) and high density lipoprotein (HDL-C)). Variables were measured at baseline, at the end of Ramadan and at 6 months post Ramadan. Results: At 6 months post Ramadan the BMI, diastolic pressure, TC, HDL-C and TC/HDL-C ratio changes were different between the two groups (except for BMI changes where P=0.02, all others P